[mythtv-users] NTSC stutter with P3 500Mhz frontend

Brian Foddy bfoddy at visi.com
Wed Aug 25 22:56:23 EDT 2004


On Wednesday 25 August 2004 09:15 pm, john roberts wrote:
> I thought a P3 500Mhz frontend only would be fast enough to avoid stutter.
> :(
>
> I've got the latest CVS built with --march=pentium3 and I'm getting stutter
> ever 3-4 sec's.
>
> mythfrontend is saying:
>
> 2004-08-25 15:11:37 prebuffering pause
> 2004-08-25 15:11:38 prebuffering pause
> 2004-08-25 15:11:39 prebuffering pause
> 2004-08-25 15:11:40 prebuffering pause
> 2004-08-25 15:11:40 prebuffering pause
> 2004-08-25 15:11:41 prebuffering pause
>
> Any ideas?  I've check to make sure drive's are set to use DMA - so no
> issues there.
>
> Backend is a P4 2.6G
> Frontend is a P3 500Mhz
>
> The odd thing is I don't see the CPU pegged at 100% - it's more like
> 75-80%.
>
> Help!!! :)
>
> -John

John,
what resolution are you capturing to?  I used to use a dual P2-450 and
the best I could muster was 480x480 or 640x240.  It just couldn't handle
the full 640x480 I wanted from a PVR250.  The fact that yours is only 
performing frontend duties is really of little help because a single pvr250
takes very little to record.  Also, since you are so close to the limit,
try turning off deinterlacing and other quality settings; every little bit
will help.

And also you might look into dropping a slightly faster CPU in the
same motherboard.  Many of the early P3 boards would accept faster
chips of the same FSB ratings that were made a few months later.
And the cost for a simple cpu upgrade is probably $50 or so.  Go
looking on pricewatch.com or someplace and if you do your homework
you can probably squeeze just enough more out of your machine to 
make it smooth.

And the fact that the CPU is only 75% busy, don't worry.  The CPU has
only so much time to process 1 frame, if it misses the mark and runs over,
then it must actually wait for another new frame.  It can't queue the
frame decodings up, it must do them in real-time.

Brian


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